Variable-lift devices, such as balloons or airships, are known in the art for moving or lifting heavy objects or objects of sizes that are too bulky for them to be transported by truck, train, helicopter or airplane. In general, such variable-lift devices are constituted by a balloon or airship containing helium or other lighter-than-air gases, such as neon, methane, ethane, or hydrogen, and in some cases having a gondola or platform attached to the balloon, such variable-lift devices being usually provided with a tank for storing the lighter-than-air gas under pressure. The balloon or airship is usually constituted by a flexible envelope supported by a rigid structure, consisting of an assembly of beams, a beam being an element that is long in one dimension relative to the other two dimensions.
For decades, private ventures and governments have struggled to transport heavy loads under harsh and difficult conditions and environmental circumstances, particularly in the arctic and other remote regions. As an example, it is not unusual for heavy-lift, short haul capabilities to be required on a frequent basis in the oil and gas and mineral exploration business in such regions, which may have no roads, or winter-only roads, or which include areas of environmental sensitivity. In some cases, at best, seasonal or temporary solutions have resulted, and some of these have been costly and limited in efficiency in many ways. Winter roads, for example, effective over several months of the year, are often viable in remote areas only over a progressively shortening cold winter season. Other transportation methods in remote areas over muskeg, permafrost and open water have relied, at least seasonally, on air transportation with its inherent costs and the need for substantial infrastructure to support it.
More recently, lighter-than-air (LTA) vehicles have been proposed for transporting heavy payloads in remote and arctic environments. However, the logistics associated with large ballast transfers generally associated with such vehicles presents substantial technical hurdles and costs, ballast transfer being required on vessels such as these in the past, since previous airships were based on using lighter-than-air gases to lift 100% of the weight of both the cargo and the vessel itself, and when such a traditional airship is not carrying cargo, the weight of the cargo must be replaced with ballast (typically water or sand) in order to maintain neutral buoyancy. While this is very fuel efficient and suitable for hauling heavy cargos long distances, this is impractical for hauling heavy loads in remote, harsh environments such as the arctic. Even where water is available for ballast, substantial planning and support equipment is required to ensure accessibility of ballast sources and that when water ballast is being utilized, the water is maintained above freezing to ensure quick and efficient payload drops and ballast management. Accordingly, there is a need for an improved air vehicle which can provide payload lifts over a distance without the need for ballast exchange, particularly in remote locations and harsh environments. There is also a need for an improved air vehicle which does not rely on aerodynamics to achieve lift or stay aloft, and which possesses a greater ease of manoeuverability to assist in picking up and delivering payloads. In this regard, the present invention substantially fulfills this need.